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<FONT color="green">001</FONT>    package maze.util;<a name="line.1"></a>
<FONT color="green">002</FONT>    <a name="line.2"></a>
<FONT color="green">003</FONT>    import java.awt.EventQueue;<a name="line.3"></a>
<FONT color="green">004</FONT>    <a name="line.4"></a>
<FONT color="green">005</FONT>    /**<a name="line.5"></a>
<FONT color="green">006</FONT>     * Implements the observer design pattern. A ListenerSubject can have Listeners<a name="line.6"></a>
<FONT color="green">007</FONT>     * registered with it and then notify those Listeners when something happens.<a name="line.7"></a>
<FONT color="green">008</FONT>     * This class can be extended or instances of it can be created to allow a class<a name="line.8"></a>
<FONT color="green">009</FONT>     * to have multiple events that can be registered with.<a name="line.9"></a>
<FONT color="green">010</FONT>     * @author Luke Last<a name="line.10"></a>
<FONT color="green">011</FONT>     * @see Listener<a name="line.11"></a>
<FONT color="green">012</FONT>     * @version 2009-05-30<a name="line.12"></a>
<FONT color="green">013</FONT>     * @param &lt;T&gt; The type of the event objects to be used by the Listeners. Objects<a name="line.13"></a>
<FONT color="green">014</FONT>     *           of this type are passed to each registered Listener when they are<a name="line.14"></a>
<FONT color="green">015</FONT>     *           notified.<a name="line.15"></a>
<FONT color="green">016</FONT>     */<a name="line.16"></a>
<FONT color="green">017</FONT>    public class ListenerSubject&lt;T&gt;<a name="line.17"></a>
<FONT color="green">018</FONT>    {<a name="line.18"></a>
<FONT color="green">019</FONT>       /**<a name="line.19"></a>
<FONT color="green">020</FONT>        * Zero, one, or many listeners. Can be null. Multiple listeners form a<a name="line.20"></a>
<FONT color="green">021</FONT>        * linked list.<a name="line.21"></a>
<FONT color="green">022</FONT>        */<a name="line.22"></a>
<FONT color="green">023</FONT>       private Listener&lt;T&gt; listener;<a name="line.23"></a>
<FONT color="green">024</FONT>    <a name="line.24"></a>
<FONT color="green">025</FONT>       /**<a name="line.25"></a>
<FONT color="green">026</FONT>        * Stores listeners that should be notified in a delayed manner. Can be null.<a name="line.26"></a>
<FONT color="green">027</FONT>        */<a name="line.27"></a>
<FONT color="green">028</FONT>       private Listener&lt;T&gt; delayedListener;<a name="line.28"></a>
<FONT color="green">029</FONT>    <a name="line.29"></a>
<FONT color="green">030</FONT>       /**<a name="line.30"></a>
<FONT color="green">031</FONT>        * Stores whether or not a delayed notify Runnable has been created on the<a name="line.31"></a>
<FONT color="green">032</FONT>        * EventQueue but not yet executed.<a name="line.32"></a>
<FONT color="green">033</FONT>        */<a name="line.33"></a>
<FONT color="green">034</FONT>       private volatile boolean pendingNotify = false;<a name="line.34"></a>
<FONT color="green">035</FONT>    <a name="line.35"></a>
<FONT color="green">036</FONT>       /**<a name="line.36"></a>
<FONT color="green">037</FONT>        * This is created when needed.<a name="line.37"></a>
<FONT color="green">038</FONT>        */<a name="line.38"></a>
<FONT color="green">039</FONT>       private DelayedNotifier delayedNotifier;<a name="line.39"></a>
<FONT color="green">040</FONT>    <a name="line.40"></a>
<FONT color="green">041</FONT>       /**<a name="line.41"></a>
<FONT color="green">042</FONT>        * Notifies all registered listeners. Normal listeners are notified<a name="line.42"></a>
<FONT color="green">043</FONT>        * Immediately, delayed listeners are notified with a new task on the event<a name="line.43"></a>
<FONT color="green">044</FONT>        * queue.<a name="line.44"></a>
<FONT color="green">045</FONT>        * @param event The event object that should be passed to each registered<a name="line.45"></a>
<FONT color="green">046</FONT>        *           Listener.<a name="line.46"></a>
<FONT color="green">047</FONT>        */<a name="line.47"></a>
<FONT color="green">048</FONT>       public final void notifyListeners(final T event)<a name="line.48"></a>
<FONT color="green">049</FONT>       {<a name="line.49"></a>
<FONT color="green">050</FONT>          final Listener&lt;T&gt; copy = this.listener;<a name="line.50"></a>
<FONT color="green">051</FONT>          if (copy != null)<a name="line.51"></a>
<FONT color="green">052</FONT>          {<a name="line.52"></a>
<FONT color="green">053</FONT>             copy.eventFired(event);<a name="line.53"></a>
<FONT color="green">054</FONT>          }<a name="line.54"></a>
<FONT color="green">055</FONT>          if (this.delayedListener != null &amp;&amp; this.pendingNotify == false)<a name="line.55"></a>
<FONT color="green">056</FONT>          {<a name="line.56"></a>
<FONT color="green">057</FONT>             this.pendingNotify = true;<a name="line.57"></a>
<FONT color="green">058</FONT>             EventQueue.invokeLater(this.getDelayedNotifier(event));<a name="line.58"></a>
<FONT color="green">059</FONT>          }<a name="line.59"></a>
<FONT color="green">060</FONT>       }<a name="line.60"></a>
<FONT color="green">061</FONT>    <a name="line.61"></a>
<FONT color="green">062</FONT>       /**<a name="line.62"></a>
<FONT color="green">063</FONT>        * This allows us to only create a new instance once and then reuse it for<a name="line.63"></a>
<FONT color="green">064</FONT>        * better performance.<a name="line.64"></a>
<FONT color="green">065</FONT>        * @param eventObject This event object is given to the notifier which it<a name="line.65"></a>
<FONT color="green">066</FONT>        *           then passes to the listeners.<a name="line.66"></a>
<FONT color="green">067</FONT>        * @return The one and only instance.<a name="line.67"></a>
<FONT color="green">068</FONT>        */<a name="line.68"></a>
<FONT color="green">069</FONT>       private DelayedNotifier getDelayedNotifier(T eventObject)<a name="line.69"></a>
<FONT color="green">070</FONT>       {<a name="line.70"></a>
<FONT color="green">071</FONT>          if (this.delayedNotifier == null)<a name="line.71"></a>
<FONT color="green">072</FONT>          {<a name="line.72"></a>
<FONT color="green">073</FONT>             this.delayedNotifier = new DelayedNotifier();<a name="line.73"></a>
<FONT color="green">074</FONT>          }<a name="line.74"></a>
<FONT color="green">075</FONT>          this.delayedNotifier.setEventObject(eventObject);<a name="line.75"></a>
<FONT color="green">076</FONT>          return this.delayedNotifier;<a name="line.76"></a>
<FONT color="green">077</FONT>       }<a name="line.77"></a>
<FONT color="green">078</FONT>    <a name="line.78"></a>
<FONT color="green">079</FONT>       /**<a name="line.79"></a>
<FONT color="green">080</FONT>        * A &lt;code&gt;Runnable&lt;/code&gt; which is invoked later on the event queue. We<a name="line.80"></a>
<FONT color="green">081</FONT>        * create a special class for this and then instantiate it only once for<a name="line.81"></a>
<FONT color="green">082</FONT>        * better performance.<a name="line.82"></a>
<FONT color="green">083</FONT>        */<a name="line.83"></a>
<FONT color="green">084</FONT>       private final class DelayedNotifier implements Runnable<a name="line.84"></a>
<FONT color="green">085</FONT>       {<a name="line.85"></a>
<FONT color="green">086</FONT>          private T eventObject;<a name="line.86"></a>
<FONT color="green">087</FONT>    <a name="line.87"></a>
<FONT color="green">088</FONT>          public void setEventObject(T eventObject)<a name="line.88"></a>
<FONT color="green">089</FONT>          {<a name="line.89"></a>
<FONT color="green">090</FONT>             this.eventObject = eventObject;<a name="line.90"></a>
<FONT color="green">091</FONT>          }<a name="line.91"></a>
<FONT color="green">092</FONT>    <a name="line.92"></a>
<FONT color="green">093</FONT>          @Override<a name="line.93"></a>
<FONT color="green">094</FONT>          public void run()<a name="line.94"></a>
<FONT color="green">095</FONT>          {<a name="line.95"></a>
<FONT color="green">096</FONT>             pendingNotify = false;<a name="line.96"></a>
<FONT color="green">097</FONT>             final Listener&lt;T&gt; delayedCopy = delayedListener;<a name="line.97"></a>
<FONT color="green">098</FONT>             if (delayedCopy != null)<a name="line.98"></a>
<FONT color="green">099</FONT>             {<a name="line.99"></a>
<FONT color="green">100</FONT>                delayedCopy.eventFired(this.eventObject);<a name="line.100"></a>
<FONT color="green">101</FONT>             }<a name="line.101"></a>
<FONT color="green">102</FONT>          }<a name="line.102"></a>
<FONT color="green">103</FONT>       }<a name="line.103"></a>
<FONT color="green">104</FONT>    <a name="line.104"></a>
<FONT color="green">105</FONT>       /**<a name="line.105"></a>
<FONT color="green">106</FONT>        * Registers a Listener with this subject. The given Listener is not checked<a name="line.106"></a>
<FONT color="green">107</FONT>        * to see if it already is registered.<a name="line.107"></a>
<FONT color="green">108</FONT>        * @param listener The Listener you would like to add.<a name="line.108"></a>
<FONT color="green">109</FONT>        */<a name="line.109"></a>
<FONT color="green">110</FONT>       public final synchronized void addListener(final Listener&lt;T&gt; listener)<a name="line.110"></a>
<FONT color="green">111</FONT>       {<a name="line.111"></a>
<FONT color="green">112</FONT>          if (listener != null)<a name="line.112"></a>
<FONT color="green">113</FONT>          {<a name="line.113"></a>
<FONT color="green">114</FONT>             if (this.listener == null)<a name="line.114"></a>
<FONT color="green">115</FONT>             {<a name="line.115"></a>
<FONT color="green">116</FONT>                this.listener = listener;<a name="line.116"></a>
<FONT color="green">117</FONT>             }<a name="line.117"></a>
<FONT color="green">118</FONT>             else<a name="line.118"></a>
<FONT color="green">119</FONT>             {<a name="line.119"></a>
<FONT color="green">120</FONT>                this.listener = new ListenerMulticaster&lt;T&gt;(this.listener, listener);<a name="line.120"></a>
<FONT color="green">121</FONT>             }<a name="line.121"></a>
<FONT color="green">122</FONT>          }<a name="line.122"></a>
<FONT color="green">123</FONT>       }<a name="line.123"></a>
<FONT color="green">124</FONT>    <a name="line.124"></a>
<FONT color="green">125</FONT>       /**<a name="line.125"></a>
<FONT color="green">126</FONT>        * @param listener<a name="line.126"></a>
<FONT color="green">127</FONT>        */<a name="line.127"></a>
<FONT color="green">128</FONT>       public final synchronized void addDelayedListener(final Listener&lt;T&gt; listener)<a name="line.128"></a>
<FONT color="green">129</FONT>       {<a name="line.129"></a>
<FONT color="green">130</FONT>          if (listener != null)<a name="line.130"></a>
<FONT color="green">131</FONT>          {<a name="line.131"></a>
<FONT color="green">132</FONT>             if (this.delayedListener == null)<a name="line.132"></a>
<FONT color="green">133</FONT>             {<a name="line.133"></a>
<FONT color="green">134</FONT>                this.delayedListener = listener;<a name="line.134"></a>
<FONT color="green">135</FONT>             }<a name="line.135"></a>
<FONT color="green">136</FONT>             else<a name="line.136"></a>
<FONT color="green">137</FONT>             {<a name="line.137"></a>
<FONT color="green">138</FONT>                this.delayedListener = new ListenerMulticaster&lt;T&gt;(this.delayedListener, listener);<a name="line.138"></a>
<FONT color="green">139</FONT>             }<a name="line.139"></a>
<FONT color="green">140</FONT>          }<a name="line.140"></a>
<FONT color="green">141</FONT>       }<a name="line.141"></a>
<FONT color="green">142</FONT>    <a name="line.142"></a>
<FONT color="green">143</FONT>       /**<a name="line.143"></a>
<FONT color="green">144</FONT>        * Unregisters a Listener with this subject. If the given listener is null or<a name="line.144"></a>
<FONT color="green">145</FONT>        * not already registered no changes are made.<a name="line.145"></a>
<FONT color="green">146</FONT>        * @param listener The Listener you want to remove.<a name="line.146"></a>
<FONT color="green">147</FONT>        */<a name="line.147"></a>
<FONT color="green">148</FONT>       public final synchronized void removeListener(final Listener&lt;T&gt; listener)<a name="line.148"></a>
<FONT color="green">149</FONT>       {<a name="line.149"></a>
<FONT color="green">150</FONT>          if (this.listener != null &amp;&amp; listener != null)<a name="line.150"></a>
<FONT color="green">151</FONT>          {<a name="line.151"></a>
<FONT color="green">152</FONT>             if (this.listener == listener)<a name="line.152"></a>
<FONT color="green">153</FONT>             {<a name="line.153"></a>
<FONT color="green">154</FONT>                this.listener = null;<a name="line.154"></a>
<FONT color="green">155</FONT>             }<a name="line.155"></a>
<FONT color="green">156</FONT>             else if (this.listener instanceof ListenerMulticaster&lt;?&gt;)<a name="line.156"></a>
<FONT color="green">157</FONT>             {<a name="line.157"></a>
<FONT color="green">158</FONT>                final ListenerMulticaster&lt;T&gt; multicaster = (ListenerMulticaster&lt;T&gt;) this.listener;<a name="line.158"></a>
<FONT color="green">159</FONT>                this.listener = multicaster.remove(listener);<a name="line.159"></a>
<FONT color="green">160</FONT>             }<a name="line.160"></a>
<FONT color="green">161</FONT>          }<a name="line.161"></a>
<FONT color="green">162</FONT>       }<a name="line.162"></a>
<FONT color="green">163</FONT>    <a name="line.163"></a>
<FONT color="green">164</FONT>       /**<a name="line.164"></a>
<FONT color="green">165</FONT>        * Removes all listeners registered with this subject.<a name="line.165"></a>
<FONT color="green">166</FONT>        */<a name="line.166"></a>
<FONT color="green">167</FONT>       public final synchronized void removeAllListeners()<a name="line.167"></a>
<FONT color="green">168</FONT>       {<a name="line.168"></a>
<FONT color="green">169</FONT>          this.listener = null;<a name="line.169"></a>
<FONT color="green">170</FONT>       }<a name="line.170"></a>
<FONT color="green">171</FONT>    <a name="line.171"></a>
<FONT color="green">172</FONT>       /**<a name="line.172"></a>
<FONT color="green">173</FONT>        * A utility class used to join 2 Listeners into one Listener interface. It<a name="line.173"></a>
<FONT color="green">174</FONT>        * is used to create a read only linked list of Listeners.&lt;br /&gt;<a name="line.174"></a>
<FONT color="green">175</FONT>        * Each instance is immutable.<a name="line.175"></a>
<FONT color="green">176</FONT>        * @author Luke Last<a name="line.176"></a>
<FONT color="green">177</FONT>        * @param &lt;T&gt;<a name="line.177"></a>
<FONT color="green">178</FONT>        */<a name="line.178"></a>
<FONT color="green">179</FONT>       private final static class ListenerMulticaster&lt;T&gt; implements Listener&lt;T&gt;<a name="line.179"></a>
<FONT color="green">180</FONT>       {<a name="line.180"></a>
<FONT color="green">181</FONT>          private final Listener&lt;T&gt; a;<a name="line.181"></a>
<FONT color="green">182</FONT>          private final Listener&lt;T&gt; b;<a name="line.182"></a>
<FONT color="green">183</FONT>    <a name="line.183"></a>
<FONT color="green">184</FONT>          /**<a name="line.184"></a>
<FONT color="green">185</FONT>           * @param a First child branch.<a name="line.185"></a>
<FONT color="green">186</FONT>           * @param b Second child branch.<a name="line.186"></a>
<FONT color="green">187</FONT>           */<a name="line.187"></a>
<FONT color="green">188</FONT>          private ListenerMulticaster(Listener&lt;T&gt; a, Listener&lt;T&gt; b)<a name="line.188"></a>
<FONT color="green">189</FONT>          {<a name="line.189"></a>
<FONT color="green">190</FONT>             this.a = a;<a name="line.190"></a>
<FONT color="green">191</FONT>             this.b = b;<a name="line.191"></a>
<FONT color="green">192</FONT>          }<a name="line.192"></a>
<FONT color="green">193</FONT>    <a name="line.193"></a>
<FONT color="green">194</FONT>          /**<a name="line.194"></a>
<FONT color="green">195</FONT>           * Removes a Listener from this linked list. Because we are immutable new<a name="line.195"></a>
<FONT color="green">196</FONT>           * instances must be created when removing an object.<a name="line.196"></a>
<FONT color="green">197</FONT>           * @param toRemove The Listener to be removed.<a name="line.197"></a>
<FONT color="green">198</FONT>           * @return The new Listener resulting from the removal. Can return itself<a name="line.198"></a>
<FONT color="green">199</FONT>           *         if nothing changed.<a name="line.199"></a>
<FONT color="green">200</FONT>           */<a name="line.200"></a>
<FONT color="green">201</FONT>          private Listener&lt;T&gt; remove(Listener&lt;T&gt; toRemove)<a name="line.201"></a>
<FONT color="green">202</FONT>          {<a name="line.202"></a>
<FONT color="green">203</FONT>             if (this.a == toRemove)<a name="line.203"></a>
<FONT color="green">204</FONT>             {<a name="line.204"></a>
<FONT color="green">205</FONT>                return this.b;<a name="line.205"></a>
<FONT color="green">206</FONT>             }<a name="line.206"></a>
<FONT color="green">207</FONT>             if (this.b == toRemove)<a name="line.207"></a>
<FONT color="green">208</FONT>             {<a name="line.208"></a>
<FONT color="green">209</FONT>                return this.a;<a name="line.209"></a>
<FONT color="green">210</FONT>             }<a name="line.210"></a>
<FONT color="green">211</FONT>             final Listener&lt;T&gt; a2;<a name="line.211"></a>
<FONT color="green">212</FONT>             final Listener&lt;T&gt; b2;<a name="line.212"></a>
<FONT color="green">213</FONT>             if (this.a instanceof ListenerMulticaster&lt;?&gt;)<a name="line.213"></a>
<FONT color="green">214</FONT>             {<a name="line.214"></a>
<FONT color="green">215</FONT>                a2 = ((ListenerMulticaster&lt;T&gt;) this.a).remove(toRemove);<a name="line.215"></a>
<FONT color="green">216</FONT>                if (this.b instanceof ListenerMulticaster&lt;?&gt;)<a name="line.216"></a>
<FONT color="green">217</FONT>                {<a name="line.217"></a>
<FONT color="green">218</FONT>                   b2 = ((ListenerMulticaster&lt;T&gt;) this.b).remove(toRemove);<a name="line.218"></a>
<FONT color="green">219</FONT>                }<a name="line.219"></a>
<FONT color="green">220</FONT>                else<a name="line.220"></a>
<FONT color="green">221</FONT>                {<a name="line.221"></a>
<FONT color="green">222</FONT>                   b2 = this.b; // B is not a multicaster.<a name="line.222"></a>
<FONT color="green">223</FONT>                }<a name="line.223"></a>
<FONT color="green">224</FONT>             }<a name="line.224"></a>
<FONT color="green">225</FONT>             else<a name="line.225"></a>
<FONT color="green">226</FONT>             { // A is not a multicaster.<a name="line.226"></a>
<FONT color="green">227</FONT>                a2 = this.a;<a name="line.227"></a>
<FONT color="green">228</FONT>                if (this.b instanceof ListenerMulticaster&lt;?&gt;)<a name="line.228"></a>
<FONT color="green">229</FONT>                {<a name="line.229"></a>
<FONT color="green">230</FONT>                   b2 = ((ListenerMulticaster&lt;T&gt;) this.b).remove(toRemove);<a name="line.230"></a>
<FONT color="green">231</FONT>                }<a name="line.231"></a>
<FONT color="green">232</FONT>                else<a name="line.232"></a>
<FONT color="green">233</FONT>                {<a name="line.233"></a>
<FONT color="green">234</FONT>                   return this; // A nor B are multicasters.<a name="line.234"></a>
<FONT color="green">235</FONT>                }<a name="line.235"></a>
<FONT color="green">236</FONT>             }<a name="line.236"></a>
<FONT color="green">237</FONT>             return new ListenerMulticaster&lt;T&gt;(a2, b2);<a name="line.237"></a>
<FONT color="green">238</FONT>          }<a name="line.238"></a>
<FONT color="green">239</FONT>    <a name="line.239"></a>
<FONT color="green">240</FONT>          /**<a name="line.240"></a>
<FONT color="green">241</FONT>           * Passes the event on to children.<a name="line.241"></a>
<FONT color="green">242</FONT>           */<a name="line.242"></a>
<FONT color="green">243</FONT>          @Override<a name="line.243"></a>
<FONT color="green">244</FONT>          public void eventFired(final T event)<a name="line.244"></a>
<FONT color="green">245</FONT>          {<a name="line.245"></a>
<FONT color="green">246</FONT>             if (this.a != null)<a name="line.246"></a>
<FONT color="green">247</FONT>             {<a name="line.247"></a>
<FONT color="green">248</FONT>                this.a.eventFired(event);<a name="line.248"></a>
<FONT color="green">249</FONT>             }<a name="line.249"></a>
<FONT color="green">250</FONT>             if (this.b != null)<a name="line.250"></a>
<FONT color="green">251</FONT>             {<a name="line.251"></a>
<FONT color="green">252</FONT>                this.b.eventFired(event);<a name="line.252"></a>
<FONT color="green">253</FONT>             }<a name="line.253"></a>
<FONT color="green">254</FONT>          }<a name="line.254"></a>
<FONT color="green">255</FONT>       }<a name="line.255"></a>
<FONT color="green">256</FONT>    }<a name="line.256"></a>




























































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